Method and apparatus for acquiring information on access point in wireless communication system

ABSTRACT

An AP information management entity of a cellular system transmits a request for information on an AP to an AP server, and receives a response, which includes a result code of the request, from the AP server. The AP information management entity of the cellular system may be one of an eNodeB (eNB), mobility management entity (MME), or a new entity of the cellular system.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to wireless communications, and morespecifically, to a method and apparatus for acquiring information on anaccess point (AP) in a wireless communication system.

Related Art

With the recent trend of increasing high-rate data traffic, fifthgeneration mobile communication technologies are in discussion for theirrealistic and efficient backup. One of requirements for fifth generationmobile communication technologies is the interworking betweenheterogeneous wireless communication systems, particularly between acellular system and a wireless LAN (WLAN) system. The cellular systemmay be one of a 3^(rd) generation partnership project (3GPP) long-termevolution (LTE) system, a 3GPP LTE-A (advanced) system, and an instituteof electrical and electronics engineers (IEEE) 802.16 (WiMax, WiBro)system. The WLAN system may be an IEEE 802.11 (Wi-Fi) system. Inparticular, WLAN is a wireless communication system that is commonlyused for various user equipments, and thus, the cellular-WLANinteroperation is a high-priority convergence technique. Offloading bythe cellular-WLAN interoperation may increase the coverage and capacityof the cellular system.

The arrival of the ubiquitous environment led to a sharp increase indemand for seamless services anytime, anywhere. The fifth generationmobile communication system may adopt a plurality of radio accesstechnologies (RATs) for always gaining easy access and maintainingefficient performance in any place. In other words, the fifth-generationmobile communication system may use multiple RATs in a converging mannerthrough the interoperation between heterogeneous wireless communicationsystems. Each entity in the plurality of RATs constituting afifth-generation mobile communication system may exchange informationtherebetween, and accordingly, the optimal communication system may beprovided to a user in the fifth-generation mobile communication system.Among the plurality of RATs constituting the fifth-generation mobilecommunication system, a specific RAT may operate as a primary RATsystem, and another specific RAT may operate as a secondary RAT system.That is, the primary RAT system may mainly play a role to provide acommunication system to a user in the fifth-generation mobilecommunication system, while the secondary RAT system may assist theprimary RAT system. In general, a 3GPP LTE(-A) or IEEE 802.16 cellularsystem with relatively broad coverage may be a primary RAT system, and aWi-Fi system with relatively narrower coverage may be a secondary RATsystem.

In a fifth-generation mobile communication system constituted of aplurality of RATs, a primary RAT system needs to grasp the entities of asecondary RAT system that operates within its own coverage. For example,in case that a primary RAT system is a cellular system, and a secondaryRAT system is a Wi-Fi system, a cellular node such as an eNodeB (eNB),mobility management entity (MME), or new cellular entity need be awareof which access points (APs) are in operation within its coverage. Anentity of a secondary RAT system may report information on the entity ofthe second RAT system to a management device (for example, a managementserver). An AP information management entity in the cellular system,e.g., eNB, MME, or new entity, may acquire information on APs within anarea, which is managed by AP information management entity, from aseparate management server. For example, if the AP informationmanagement entity is the eNB, the eNB may acquire information on APswithin its coverage.

When an AP information management server is located within a cellularnetwork, there is a need for a method for acquiring, by an APinformation management entity in the cellular network, information onAPs from the AP information management server through a cellular systeminterface.

SUMMARY OF THE INVENTION

The present invention provides a method and apparatus for acquiringinformation on access points (APs) in a wireless communication system.The present invention provides a method for acquiring, by an APinformation management entity of a primary radio access technology (RAT)system, information on APs in a secondary RAT system from an APinformation management server which is located within the primary RATsystem. The present invention provides a method for acquiring, by an APinformation management entity of a primary RAT system, information onAPs from an AP information management server through various interfacesbetween the AP information management entity and the AP informationmanagement server.

In an aspect, a method for acquiring, by an eNodeB (eNB) of a cellularsystem, information on an access point (AP) in a wireless communicationsystem is provided. The method includes transmitting a request forinformation on an AP, which is located within coverage of the eNB, to anAP server, and receiving a response, which includes a result code of therequest, from the AP server.

The request may be transmitted to the AP server through a mobilitymanagement entity (MME) using an S1 application protocol, and theresponse may be received from the AP server through the MME using the S1application protocol.

The request may include at least one of a request range flag of the eNB,and a cell identity (ID).

The request may be transmitted to the AP server directly using a newlydefined interface, and the response may be received from the AP serverdirectly using the newly defined interface.

The request may include at least one of an ID of the eNB, a requestrange flag, a cell ID, a public land mobile network (PLMN) ID, locationof the eNB, and coverage of the eNB.

The result code of the request may be ‘success’, and the response mayfurther include the information on the AP.

The information on the AP may include at least one of a media accesscontrol (MAC) address of the AP, a service set identifier (SSID) of theAP, a homogeneous extended service set ID (HESSID) of the AP, whether ofthe AP can be used by a limited user, information on a frequency channelused by the AP, and a position of the AP.

In another aspect, a method for acquiring, by a mobility managemententity (MME) of a cellular system, information on an access point (AP)in a wireless communication system is provided. The method includestransmitting a request for information on an AP, which is located withincoverage of an eNodeB (eNB) managed by the MME, to an AP server using anewly defined interface, and receiving a response, which includes aresult code of the request, from the AP server using the newly definedinterface.

In another aspect, a method for transmitting, by an access point (AP)server, information on an AP in a wireless communication system isprovided. The method includes receiving a request for information on anAP to an entity of a cellular system which manages the information onthe AP, and transmitting a response, which includes a result code of therequest, to the entity of the cellular system.

Information on APs can be acquired efficiently when an AP informationmanagement server is located within a cellular network.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a cellular system.

FIG. 2 shows a structure of a radio frame in 3GPP LTE.

FIG. 3 shows a wireless local area network (WLAN) system.

FIG. 4 shows an example of a frame structure of IEEE 802.11.

FIG. 5 shows an example of a scenario of a converged communicationsystem of a cellular system and a Wi-Fi system.

FIG. 6 shows an example of a structure of a system in which an eNB,which is an AP information management entity, may acquire AP informationfrom an AP server according to an embodiment of the present invention.

FIG. 7 shows an example of a method in which an eNB, which is an APinformation management entity, acquires AP information from an AP serveraccording to an embodiment of the present invention.

FIG. 8 shows an example of a structure of a system in which an eNB,which is an AP information management entity, may acquire AP informationfrom an AP server according to another embodiment of the presentinvention.

FIG. 9 shows an example of a method in which an eNB, which is an APinformation management entity, acquires AP information from an AP serveraccording to another embodiment of the present invention.

FIG. 10 shows an example of a method in which a cellular entity, whichis an AP information management entity, acquires AP information from anAP server according to an embodiment of the present invention.

FIG. 11 is an example of a method of acquiring information on a cellularsystem using a multi-RAT device in an active state.

FIG. 12 is an example of a method of acquiring information on a cellularsystem using a multi-RAT device in an idle state.

FIG. 13 is a block diagram showing wireless communication system toimplement an embodiment of the present invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

A technology below can be used in a variety of wireless communicationsystems, such as code division multiple access (CDMA), frequencydivision multiple access (FDMA), time division multiple access (TDMA),orthogonal frequency division multiple access (OFDMA), and singlecarrier frequency division multiple access (SC-FDMA). CDMA can beimplemented using radio technology, such as universal terrestrial radioaccess (UTRA) or CDMA2000. TDMA can be implemented using radiotechnology, such as global system for mobile communications(GSM)/general packet radio service (GPRS)/enhanced data rates for GSMevolution (EDGE). OFDMA can be implemented using radio technology, suchas IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, or EvolvedUTRA (E-UTRA). IEEE 802.16m is the evolution of IEEE 802.16e, and itprovides a backward compatibility with an IEEE 802.16e-based system.UTRA is part of a universal mobile telecommunications system (UMTS). 3rdgeneration partnership project (3GPP) long term evolution (LTE) is partof evolved UMTS (E-UMTS) using evolved-UMTS terrestrial radio access(E-UTRA), and it adopts OFDMA in downlink (DL) and SC-FDMA in uplink(UL). LTE-A (advanced) is the evolution of 3GPP LTE.

3GPP LTE(-A) and IEEE 802.11 are chiefly described as an example inorder to clarify the description, but the technical spirit of thepresent invention is not limited to 3GPP LTE(-A) and IEEE 802.11.

FIG. 1 shows a cellular system.

Referring to FIG. 1, the cellular system 10 includes one or more basestations (BSs) 11. The BSs 11 provide communication services torespective geographical areas (in general called ‘cells’) 15 a, 15 b,and 15 c. Each of the cells can be divided into a number of areas(called ‘sectors’). A user equipment (UE) 12 can be fixed or mobile andmay be referred to as another terminology, such as a mobile station(MS), a mobile terminal (MT), a user terminal (UT), a subscriber station(SS), a wireless device, a personal digital assistant (PDA), a wirelessmodem, or a handheld device. In general, the BS 11 refers to a fixedstation that communicates with the UEs 12, and it may be referred to asanother terminology, such as an evolved-NodeB (eNB), a base transceiversystem (BTS), or an access point.

The UE generally belongs to one cell. A cell to which a UE belongs iscalled a serving cell. A BS providing the serving cell withcommunication services is called a serving BS. A wireless communicationsystem is a cellular system, and so it includes other cells neighboringa serving cell. Other cells neighboring the serving cell are calledneighbor cells. A BS providing the neighbor cells with communicationservices is called as a neighbor BS. The serving cell and the neighborcells are relatively determined on the basis of a UE.

This technology can be used in the downlink (DL) or the uplink (UL). Ingeneral, DL refers to communication from the BS 11 to the UE 12, and ULrefers to communication from the UE 12 to the BS 11. In the DL, atransmitter may be part of the BS 11 and a receiver may be part of theUE 12. In the UL, a transmitter may be part of the UE 12 and a receivermay be part of the BS 11.

FIG. 2 shows a structure of a radio frame in 3GPP LTE. It may bereferred to Section 4 of 3GPP TS 36.211 V8.2.0 (2008-03).

Referring to FIG. 2, the radio frame includes 10 subframes, and onesubframe includes two slots. The slots in the radio frame are numberedby #0 to #19. A transmission time interval (TTI) is a scheduling unitfor a data transmission. In 3GPP LTE, one TTI may be identical with atime taken for transmitting one subframe. A radio frame may have alength of 10 ms, a subframe may have a length of 1 ms, and a slot mayhave a length of 0.5 ms.

One slot includes a plurality of orthogonal frequency divisionmultiplexing (OFDM) symbols in a time domain and a plurality ofsubcarriers in a frequency domain. Since 3GPP LTE uses OFDMA indownlink, the OFDM symbols are used to express a symbol period. The OFDMsymbols may be called by other names depending on a multiple-accessscheme. For example, when a single carrier frequency division multipleaccess (SC-FDMA) is in use as an uplink multi-access scheme, the OFDMsymbols may be called SC-FDMA symbols. A resource block (RB), a resourceallocation unit, includes a plurality of continuous subcarriers in aslot. The structure of the radio frame is merely an example. Namely, thenumber of subframes included in a radio frame, the number of slotsincluded in a subframe, or the number of OFDM symbols included in a slotmay vary.

3GPP LTE defines that one slot includes seven OFDM symbols in a normalcyclic prefix (CP) and one slot includes six OFDM symbols in an extendedCP.

FIG. 3 shows a wireless local area network (WLAN) system.

The WLAN system may also be referred to as a Wi-Fi system. Referring toFIG. 3, the WLAN system includes one access point (AP) 20 and aplurality of stations (STAs) 31, 32, 33, 34, and 4). The AP 20 may belinked to each STA 31, 32, 33, 34, and 40 and may communicate therewith.The WLAN system includes one or more basic service sets (BSSs). The BSSis a set of STAs that may be successfully synchronized with each otherand may communicate with each other, and does not mean a specificregion.

An infrastructure BSS includes one or more non-AP stations, APs thatprovide a distribution service (DS), and a DS that links a plurality ofAPs with each other. In the infrastructure BSS, an AP manages non-APSTAs of the BSS. Accordingly, the WLAN system shown in FIG. 3 mayinclude an infrastructure BSS. In contrast, an independent BSS (IBSS) isa BSS that operates in ad-hoc mode. The IBSS does not include an AP andthus lacks a centralized management entity. That is, in the IBSS, thenon-AP STAs are managed in a distributed manner. The IBSS may have allthe STAs constituted of mobile STAs and is not allowed to access thedistribution system, thus achieving a self-contained network.

The STA is random functional medium that includes a physical layerinterface for a wireless medium and an media access control (MAC))observing IEEE 802.11 standards, and in its broader concepts, itincludes both the AP and non-AP station.

The non-AP STA is an STA, not an AP. The non-AP STA may also be referredto as a mobile terminal, a wireless device, a wireless transmit/receiveunit (WTRU), a user equipment (UE), a mobile station (MS), a mobilesubscriber unit or simply as a user. Hereinafter, for ease ofdescription, the non-AP STA denotes an STA.

The AP is a functional entity that provides access to a distributionsystem via a wireless medium for an STA associated with the AP. In theinfrastructure BSS including an AP, communication between STAs isbasically done via an AP, but in case a direct link is established,direct communication may be achieved between STAs. The AP may also bereferred to as a central controller, a base station (BS), a NodeB, abase transceiver system (BTS), or a site controller.

A plurality of infrastructure BSSs may be linked with each anotherthrough a distribution system. The plurality of BSSs linked with eachanother is referred to as an extended service set (ESS). The APs and/orSTAs included in the ESS may communicate with each other, and in thesame ESS, an STA may move from one BSS to another, while in seamlesscommunication.

FIG. 4 shows an example of a frame structure of IEEE 802.11.

A frame of IEEE 802.11 includes a set of fields in a fixed order.Referring to FIG. 4, the frame of IEEE 802.11 includes a frame controlfield, a duration/ID field, an address 1 field, an address 2 field, anaddress 3 field, a sequence control field, an address 4 field, a qualityof service (QoS) control field, an HT control field, a frame body field,and a frame check sequence (FCS) field. Among the fields listed above,the frame control field, the duration/ID field, the address 1 field, andthe FCS field constitute a minimum IEEE 802.11 frame format, and may beincluded in all IEEE 802.11 frames. The address 2 field, the address 3field, the sequence control field, the address 4 field, the QoS controlfield, the HT control field, and the frame body field may be includedonly in a specific frame type.

The frame control field may include various subfields. The duration/IDfield may be 16 bits in length. The address field may include a basicservice set identifier (BSSID), a source address (SA), a destinationaddress (DA), a transmitting STA address (TA), and a receiving STAaddress (RA). In the address field, different fields may be used forother purposes according to a frame type. The sequence control field canbe used when fragments are reassembled or when an overlapping frame isdiscarded. The sequence control field may be 16 bits, and may includetwo subfields indicating a sequence number and a fragment number. TheFCS field can be used to check an error of a frame received by astation. The FCS field may be a 32-bit field including a 32-bit cyclicredundancy check (CRC). An FCS can be calculated across the frame bodyfield and all fields of a media access control (MAC) header.

The frame body field may include information specified for an individualframe type and subtype. That is, the frame body field carries high-leveldata from one station to another station. The frame body field can alsobe called a data field. The frame body field can be variously changed inlength. A minimum length of the frame body field may be zero octet. Amaximum length of the frame body field may be determined by a total sumof a maximum length of a MAC service data unit (MSDU), a length of amesh control field, and an overhead for encryption or a total sum of amaximum length of an aggregated MSDU (A-MSDU) and an overhead forencryption. The data frame includes high-level protocol data of theframe body field. The data frame may always include the frame controlfield, the duration/ID field, the address 1 field, the address 2 field,the address 3 field, the sequence control field, the frame body field,and the FCS field. A presence of an address 4 field may be determined bya configuration of a ‘To DS’ subfield and a ‘From DS’ subfield in theframe control field. Another data frame type can be categorizedaccording to a function.

A management frame may always include the frame control field, theduration/ID field, the address 1 field, the address 2 field, the address3 field, the sequence control field, the frame body field, and the FCSfield. Data included in the frame body field generally uses afixed-length field called a fixed field and a variable-length fieldcalled an information element. The information element is avariable-length data unit.

The management frame can be used for various purposes according to asubtype. That is, a frame body field of a different subtype includesdifferent information. A beacon frame reports an existence of a network,and takes an important role of network maintenance. The beacon framecorresponds to a parameter which allows a mobile station to participatein the network. In addition, the beacon frame is periodicallytransmitted so that the mobile station can scan and recognize thenetwork. A probe request frame is used to scan an IEEE 802.11 network inwhich the mobile station exists. A probe response frame is a responsefor the probe request frame. An authentication request is used so thatthe mobile station requests an access point to perform authentication.An authentication response frame is a response for the authenticationrequest frame. A de-authentication frame is used to finish anauthentication relation. An association request frame is transmitted sothat the mobile station participates in the network when the mobilestation recognizes the compatible network and is authenticated. Anassociation response frame is a response for the association requestframe. A de-association frame is used to finish an association relation.

Three states may exist according to an authentication and associationprocedure in IEEE 802.11. Table 1 below shows the three states of IEEE802.11.

TABLE 1 Authentication Association State 1 X X State 2 ◯ X State 3 ◯ ◯

To transmit a data frame, a device must perform the authentication andassociation procedure with respect to a network. In Table 1, a procedureof transitioning from the state 1 to the state 2 can be called theauthentication procedure. The authentication procedure can be performedin such a manner that one device acquires information on a differentdevice and authenticates the different device. The information on thedifferent device can be acquired by using two methods, i.e., a passivescanning method for acquiring information on a different node byreceiving a beacon frame and an active scanning method for acquiring theinformation on the different device by transmitting a probe requestmessage and receiving a probe response message received in responsethereto. The authentication procedure can be complete by exchanging anauthentication request frame and an authentication response frame.

In Table 1, a procedure of transitioning from the state 2 to the state 3can be called the association procedure. The association procedure canbe complete when two devices exchange the association request frame andthe association response frame upon completion of the authenticationprocedure. An association ID can be allocated by the associationprocedure.

FIG. 5 shows an example of a scenario of a converged communicationsystem of a cellular system and a Wi-Fi system.

It is assumed in FIG. 5 that the cellular system operates as a primaryRAT system of the converged communication system, and the Wi-Fi systemoperates as a secondary RAT system of the converged communicationsystem. Further, the cellular system may be a 3GPP LTE(-A) system.Hereinafter, for ease of description, it is assumed that the primary RATsystem of the converged communication system is a 3GPP LTE(-A) system,and the secondary RAT system of the communication system is an IEEE802.11 system, i.e., a Wi-Fi system. However, embodiments of the presentinvention are not limited thereto.

Referring to FIG. 5, there are a plurality of general devices 61, 62,63, 64, and 65 in the coverage of the cellular base station 50. Each ofthe general devices 61, 62, 63, 64, and 65 may be a user equipment in acellular system. The cellular base station 50 may communicate with eachof the general devices 61, 62, 63, 64, and 65 via a cellular radiointerface. For example, the cellular base station 50 may perform voicecall communication with each of the general devices 61, 62, 63, 64, and65 or may control access of each general device 61, 62, 63, 64, and 65to a Wi-Fi system.

The cellular base station 50 is connected to a serving gateway(S-GW)/mobility management entity (MME) 70 through a cellular systeminterface. The MME contains a user equipment's access information orinformation on a user equipment's capability, and such information maybe mainly used for mobility management. The MME is in charge of acontrol plane. The S-GW is a gateway having an E-UTRAN as an end point.The S-GW is in charge of a user plane. The S-GW/MME 70 is connected to apacket data network (PDN) gateway (P-GW) 71 and a home subscriber server(HSS) 72 through the cellular system interface. The PDN-GW is a gatewayhaving a PDN as an end point.

The P-GW 71 and the HSS 72 are connected to a 3GPP access authenticationauthorization (AAA) server 73 through the cellular system interface. TheP-GW 71 and the 3GPP AAA server 73 may be connected to an evolved packetdata gateway (e-PDG) 74 through the cellular system interface. The e-PDG74 may be included only in untrusted non-3GPP access. The e-PDG 74 maybe connected to a WLAN access gateway (WAG) 75. The WAG 75 may be incharge of a P-GW in a Wi-Fi system.

Meanwhile, a plurality of APs 81, 82, and 83 may be present in thecoverage of the cellular base station 50. Each of the APs 81, 82, and 83may have coverage which is shorter than that of the cellular basestation 50. Each of the APs 81, 82, and 83 may communicate with generaldevices 61, 62, and 63 that are present in its coverage through a Wi-Firadio interface. In other words, the general devices 61, 62, and 63 maycommunicate with the cellular base station 50 and/or APs 81, 82, and 83.Communication methods of the general devices 61, 62, and 63 are asfollows:

1) Cellular/Wi-Fi simultaneous radio transmission: the general device 61may perform high-speed data communication with the AP 81 through a Wi-Firadio interface while communicating with the cellular base station 50through a cellular radio interface.

2) Cellular/Wi-Fi user plane automatic shift: the general device 62 maycommunicate with one of the cellular base station 50 and the AP 82 byuser plane automatic shift. At this time, the control plane may bepresent in both the cellular system and the Wi-Fi system or only in thecellular system.

3) Terminal cooperative transmission: the general device 64 operating asa source device may directly communicate with the cellular base station50 through a cellular radio interface or may indirectly communicate withthe cellular base station 50 through a general device 65 operating as acooperative device. That is, the cooperative device 65 may assist thesource device 64 so that the source device 64 may indirectly communicatewith the cellular base station 50 through itself The source device 64and the cooperative device 65 communicate with each other through aWi-Fi radio interface.

4) Wi-Fi-based cellular link control mechanism: the AP 83 may perform acellular link control mechanism such as paging or location registrationof a network for the cellular general device 63. The general device 63is not directly connected to the cellular base station 50 and maydirectly communicate with the cellular base station 50 thorough the AP83.

Each of the APs 81, 82, and 83 is connected to the WAG 75 through aWi-Fi system interface.

A method for acquiring, by an AP information management entity of aprimary RAT system, information on APs in a secondary RAT system from anAP information management server, which is located within the primaryRAT system, according to embodiments of the present invention isdescribed below. Hereinafter, for convenience of the description, it isassumed that the primary RAT system is a 3GPP LTE (or 3GPP LTE-A) whichis a cellular system, and the secondary RAT system an IEEE 802.11(Wi-Fi) which is a WLAN system. However, the embodiment of the presentinvention is not limited thereto. When the primary RAT system is a 3GPPLTE(-A), the AP information management entity of a primary RAT systemmay be one of an eNB, MME or new entity.

The AP information management server may be a device to provide ageneric advertisement service (GAS) using an access network queryprotocol (ANQP). The ANQP is a query protocol for access networkinformation retrieval transported by GAS public action frames. GASprovides functionality that enables STAs to discover the availability ofinformation related to desired network services, e.g., information aboutservices such as provided in an IBSS, local access services, availablesubscription service providers (SSPs) and/or subscription serviceprovider networks (SSPNs) or other external networks. GAS uses a genericcontainer to advertise network services' information over an IEEE 802.11network. Public action frames are used to transport this information.Further, the AP information management server may be a WAG. A new entitymay be added between the AP and the management server so that acorresponding entity may combine information on the cellular systemtransmitted from the AP, change a transmission format, and transmit thecombined information to the management server. The added new entity maybe a dual-stack gateway or an AP controller, etc. Or, in the descriptionabove, the AP information management server may be a device providing anaccess network discovery and selection function (ANDSF).

1) First, a scenario in which an eNB, which is an AP informationmanagement entity, acquires AP information from an AP informationmanagement server (Hereinafter, an AP server) through the MME isdescribed.

FIG. 6 shows an example of a structure of a system in which an eNB,which is an AP information management entity, may acquire AP informationfrom an AP server according to an embodiment of the present invention.Referring to FIG. 6, when a structure of a convergence system of acellular system and a Wi-Fi system described in FIG. 5 is used, the APserver exists within the cellular system. The AP server may be connectedto an S-GW/MME through a new cellular system interface for acquiring APinformation. The eNB, which is an AP information management entity, mayacquire AP information from the AP server through a new cellular systeminterface between the S-GW/MME and the AP server.

FIG. 7 shows an example of a method in which an eNB, which is an APinformation management entity, acquires AP information from an AP serveraccording to an embodiment of the present invention.

In step S100, in order for an eNB1/eNB2 to acquire information of an APexisting within coverage thereof, the eNB1/eNB2 transmits a secondaryRAT information request to an MME. For example, the eNB may transmit asecondary RAT information request to the MME at a time point at whichthe eNB first turns on power or at a time point that determines that itis necessary to apply convergence of the cellular system and the Wi-Fisystem to devices within coverage of the eNB. Because AP information isnot UE specific information, the secondary RAT information request maybe non-UE associated signaling.

When the eNB transmits the secondary RAT information request, an S1application protocol, which is an existing cellular system interface,may be used. When the eNB and the MME perform an AP informationrequest/response through an S1 interface, transmitted messages each areidentified by a Message Type information element (IE). Table 2represents an example of Message Type IE.

TABLE 2 IE/Group Semantics Name Presence Range IE type and referencedescription Message Assumed Type max no of messages is 256. >Procedure M(Handover Preparation, Handover Resource Code Allocation, HandoverNotification, Path Switch Request, Handover Cancellation, E- RAB Setup,E-RAB Modify, E-RAB Release, E-RAB Release Indication, Initial ContextSetup, Paging, Downlink NAS transport, Initial UE Message, Uplink NAStransport, Reset, Error Indication, NAS Non Delivery Indication, S1Setup, UE Context Release Request, UE Context Release, Downlink S1CDMA2000 Tunneling, Uplink S1 CDMA2000 Tunneling; UE ContextModification, UE Capability Info Indication, eNB Status Transfer, MMEStatus Transfer, Deactivate Trace, Trace Start, Trace FailureIndication, eNB Configuration Update, MME Configuration Update, LocationReporting Control, Location Reporting Failure Indication, LocationReport, Overload Start, Overload Stop, Private Message, Write-ReplaceWarning, eNB Direct Information Transfer, MME Direct InformationTransfer, Cell Traffic Trace, eNB Configuration Transfer, MMEConfiguration Transfer, Downlink UE Associated LPPa transport, Uplink UEAssociated LPPa transport, Downlink Non UE Associated LPPa transport,Uplink Non UE Associated LPPa transport, Kill, UE Radio CapabilityMatch, . . .) >Type of M CHOICE (Initiating Message, Message SuccessfulOutcome, Unsuccessful Outcome, . . .)

Referring to Table 2, Message Type IE includes a Procedure Code field.The Procedure Code field may be an id-SecondaryRATInformationRequest.Accordingly, it may be seen that a corresponding message is a messagerelated to AP information acquisition. Further, Message Type IE includesa Type of Message field. When the Procedure Code field is anid-SecondaryRATInformationRequest, the Type of Message field may be oneof ‘Initiating Message’, ‘Successful Outcome’, and ‘UnsuccessfulOutcome’. For example, when the Type of Message field is an ‘Initiatingmessage’, this is a secondary RAT information request in which the eNBtransmits to the MME, and a corresponding message becomes aSecondaryRATInformationRequest message. Alternatively, when a Type ofMessage field is ‘Successful Outcome’, this is a response in which theMME transmits to the eNB when a request of the eNB is succeeded, and acorresponding message becomes aSecondaryRATInformationRequestAcknowledge message. This will bedescribed later. Alternatively, when a Type of Message field is‘Unsuccessful Outcome’, this is a response in which the MME transmits tothe eNB when a request of the eNB is failed, and a corresponding messagebecomes a SecondaryRATInformationRequestFailure message. This will bedescribed later. Further, criticality of the Message Type IE may be‘reject’. This is error handling when the MME cannot recognize oranalyze a request of the eNB and represents that a reject procedure isperformed.

Further, the secondary RAT information request may include a requestrange flag. When the request range flag is ‘all’, this represents thatthe eNB requests information of APs within managing entire cells. Whenthe request range flag is ‘specific cell(s)’, this represents that theeNB requests information of an AP within a specific cell among managingcells. That is, the request range flag indicates a range in which theeNB requests AP information. Further, the secondary RAT informationrequest may further include a cell ID. This may be physical cell IDaccording to an AP information request range.

In step S110, upon receiving the secondary RAT information request fromthe eNB, the MME transmits a secondary RAT configuration acquisitionservice setup request to the AP server and requests service registrationfor acquiring AP information. The MME may request only information ofthe AP corresponding to the eNB, which transmits the secondary RATinformation request. Alternatively, the MME may request information ofAPs corresponding to all or a part of eNBs which the MME manages. For aneNB which does not transmit the secondary RAT information request, thismay be terminated with onetime acquisition event.

In order for the MME to transmit a secondary RAT configurationacquisition service setup request to the AP server, a new cellularsystem interface may be defined between the MME and the AP server.Further, a Command-Code value for identifying the secondary RATconfiguration acquisition service setup request transmitted through anew cellular system interface may be defined. The Command-Code value maybe allocated by Internet assigned numbers authority (IANA) in Internetengineering task force (IETF) request for comments (RFC) 5516.

Further, the secondary RAT configuration acquisition service setuprequest may include identifier information of corresponding each eNBaccording to an AP information request range. The identifier informationof each eNB may include each eNB ID, a request range flag of each eNB,cell ID of each eNB, public land mobile network (PLMN) ID, and alocation and coverage of each eNB. A combination of PLMN ID, eNB ID, andcell ID may be a format of E-UTRAN cell ID (ECI) or E-UTRAN cell globalID (ECGI). Further, like PLMN ID, identifier information that is commonto each eNB, may be included only one time within the secondary RATconfiguration acquisition service setup request.

In step S120, upon receiving the secondary RAT configuration acquisitionservice setup request from the MME, the AP server transmits a secondaryRAT configuration acquisition service setup answer to the MME. Thesecondary RAT configuration acquisition service setup answer may includeAP information according to a request of the MME. The AP server mayextract information of an AP within coverage of a minimum unit (e.g., acell) of a request according to an AP information request range andinclude the information of the AP in the secondary RAT configurationacquisition service setup answer. Further, the secondary RATconfiguration acquisition service setup answer may include a result codeto the request of the MME, PLMN ID, eNB ID, cell ID, and a location andcoverage of the eNB. The secondary RAT configuration acquisition servicesetup answer may be transmitted through a newly defined cellular systeminterface between the AP server and the MME. A Command-Code value foridentifying the secondary RAT configuration acquisition service setupanswer may be defined. The Command-Code value may be allocated by IANAin IETF RFC 5516.

AP information on a minimum unit of a request included in the secondaryRAT configuration acquisition service setup answer may include a MACaddress (BSSID) of the AP, SSID of the AP, information on whether the APis an AP in which only a limited user can use (closed subscriber group(CSG) and password/open subscriber group (OSG), homogeneous ESS ID(HESSID) of the AP, information (operating class and channel number)about a frequency channel in which the AP uses, and a location of theAP.

The result code included in the secondary RAT configuration acquisitionservice setup answer may be set to one of ‘success’, ‘failure 1’, and‘failure 2’. A result code set to ‘success’ represents that a request ofthe MME was succeeded. A result code set to ‘failure 1’ represents thata request of the MME was failed. A result code set to ‘failure 2’represents that a request of the MME may not be satisfied at a timepoint that receives a request of the MME, but may be satisfied later.When the result code is set to ‘failure 2’, the AP server may furtherinclude a time point that can respond to a request of the MME in thesecondary RAT configuration acquisition service setup answer.Alternatively, the AP server may notify the MME that the AP server mayrespond at a time point that can respond to a request of the MME or maytransmit corresponding AP information at a time point that can respondto a request of the MME.

In step S130, upon receiving the secondary RAT configuration acquisitionservice setup answer from the AP server, the MME transmits secondary RATinformation request acknowledge or secondary RAT information requestfailure to each eNB. The MME receives the secondary RAT configurationacquisition service setup answer and determines a result code within thesecondary RAT configuration acquisition service setup answer. When theresult code is ‘success’, the MME transmits secondary RAT informationrequest acknowledge including AP information on a minimum unit of arequest corresponding to each eNB to the each eNB. When the result codeis ‘failure’ (including failure 1 and failure 2), the MME transmitssecondary RAT information request failure to corresponding each eNB. InFIG. 7, it is assumed that the result code is ‘success’.

Secondary RAT information request acknowledge or secondary RATinformation request failure may be transmitted using an S1 applicationprotocol. Secondary RAT information request acknowledge may betransmitted through a SecondaryRATInformationRequestAcknowledge messagein which a type of message field is ‘Successful Outcome’. Secondary RATinformation request failure may be transmitted through aSecondaryRATInformationRequestFailure message in which a Type of Messagefield is ‘Unsuccessful Outcome’.

AP information included in the secondary RAT information requestacknowledge may include a MAC address (BSSID) of the AP, SSID of the AP,information (CSG and password/OSG) on whether the AP is an AP in whichonly a limited user can use, HESSID of the AP, information (operatingclass, channel number) about a frequency channel in which the AP uses,and a location of the AP. Further, the secondary RAT information requestacknowledge may include a cell ID. The secondary RAT information requestacknowledge or the secondary RAT information request failure may includea result code of ‘success’, ‘failure 1’, or ‘failure 2’. This may beidentical to a result code in which the AP server transmits through thesecondary RAT configuration acquisition service setup answer. When theresult code of the secondary RAT information request failure is ‘failure2’, the secondary RAT information request failure may further include are-request time point.

Upon receiving the secondary RAT information request acknowledge fromthe MME, the eNB stores received AP information on a minimum unit of arequest. Upon receiving the secondary RAT information request failurefrom the MME, the eNB determines a result code within the secondary RATinformation request failure. When the result code is ‘failure 1’, theeNB no longer requests AP information. When the result code is ‘failure2’, the eNB awaits until a re-request time point included in thesecondary RAT information request failure. The eNB may request again APinformation at a corresponding re-request time point later.

2) A scenario in which the eNB, which is an AP information managemententity, directly acquires AP information from the AP server through anewly defined cellular system interface is described.

FIG. 8 shows an example of a structure of a system in which an eNB,which is an AP information management entity, may acquire AP informationfrom an AP server according to another embodiment of the presentinvention. Referring to FIG. 8, while a structure of a convergencesystem of a cellular system and a Wi-Fi system described in FIG. 5 isused, the AP server exists within the cellular system. The AP server maybe connected to an eNB, which is an AP information management entity,through a new cellular system interface for acquiring AP information.The eNB, which is an AP information management entity, may directlyacquire AP information from the AP server through a new cellular systeminterface with the AP server.

FIG. 9 shows an example of a method in which an eNB, which is an APinformation management entity, acquires AP information from an AP serveraccording to another embodiment of the present invention.

In step S200, in order for the eNB1/eNB2 to acquire information of an APexisting within coverage thereof, the eNB1/eNB2 transmits a secondaryRAT configuration acquisition service setup request to the AP server.Accordingly, the eNB may request service registration to the AP server.For example, the eNB may transmit a secondary RAT configurationacquisition service setup request to the AP server at a time point atwhich the eNB first turns on power or at a time point that determinesthat it is necessary to apply convergence of a cellular system and aWi-Fi system to devices within coverage of the eNB. Because APinformation is not UE specific information, the secondary RATconfiguration acquisition service setup request may be non-UE associatedsignaling.

In order for the eNB to transmit the secondary RAT configurationacquisition service setup request to the AP server, a new cellularsystem interface may be defined between the eNB and the AP server.Further, a Command-Code value for identifying the secondary RATconfiguration acquisition service setup request transmitted through thenew cellular system interface may be defined. The Command-Code value maybe allocated by IANA in IETF RFC 5516.

Further, the secondary RAT configuration acquisition service setuprequest may include identifier information of the eNB according to an APinformation request range. The identifier information of the eNB mayinclude eNB ID, physical cell ID, and PLMN ID. A combination of PLMN ID,eNB ID, and cell ID may be a format of ECI or ECGI. Further, thesecondary RAT configuration acquisition service setup request mayadditionally include a request range flag and a location and coverage ofthe eNB. When the request range flag is ‘all’, this represents that theeNB requests information of APs within managing entire cells. When therequest range flag is ‘specific cell(s)’, this represents that the eNBrequests information of an AP within a specific cell among managingcells.

In step S210, upon receiving the secondary RAT configuration acquisitionservice setup request from the eNB, the AP server transmits a secondaryRAT configuration acquisition service setup answer to the eNB. Thesecondary RAT configuration acquisition service setup answer may includeAP information according to a request of each eNB. The AP server mayextract information of the AP within coverage of a minimum unit (e.g., acell) of a request according to an AP information request range andinclude the information in the secondary RAT configuration acquisitionservice setup answer. Further, the secondary RAT configurationacquisition service setup answer may include a result code to therequest of the eNB, PLMN ID, eNB ID, cell ID, and a location andcoverage of the eNB. The secondary RAT configuration acquisition servicesetup answer may be transmitted through a newly defined cellular systeminterface between the AP server and the eNB. A Command-Code value foridentifying the secondary RAT configuration acquisition service setupanswer may be defined. The Command-Code value may be allocated by IANAin IETF RFC 5516.

AP information on a minimum unit of a request included in the secondaryRAT configuration acquisition service setup answer may include a MACaddress (BSSID) of the AP, SSID of the AP, information (CSG andpassword/OSG) on whether the AP is an AP in which only a limited usercan use, HESSID of the AP, information operating class, channel number)about a frequency channel in which the AP uses, and a location of theAP.

The result code included in the secondary RAT configuration acquisitionservice setup answer may be set to any one of ‘success’, ‘failure 1’,and ‘failure 2’. A result code set to ‘success’ represents that arequest of the eNB was succeeded. A result code set to ‘failure 1’represents that a request of the eNB was failed. A result code set to‘failure 2’ represents that a request of the eNB may not be satisfied ata time point that receives a request of the eNB, but may be satisfiedlater. When the result code is set to ‘failure 2’, the AP server mayfurther additionally include a time point that can respond to a requestof the eNB in the secondary RAT configuration acquisition service setupanswer. Alternatively, the AP server may notify the eNB that the APserver may respond at a time point that can respond to a request of theeNB or may transmit corresponding AP information at a time point thatcan respond to a request of the eNB.

Upon receiving the secondary RAT configuration acquisition service setupanswer from the AP server, the eNB determines a result code within thesecondary RAT configuration acquisition service setup answer. When theresult code is ‘success’, the eNB stores AP information that receives ona minimum unit of a request. When the result code is ‘failure 1’, theeNB no longer requests AP information. When the result code is ‘failure2’, the eNB awaits until a time point, in which the AP server canrespond to a request of the eNB, included in the secondary RATconfiguration acquisition service setup answer. The eNB may requestagain AP information at a time point at which the AP server can respondto a request of the eNB.

3) A scenario in which a MME or a new entity, which is an AP informationmanagement entity, acquires AP information from the AP server through anewly defined cellular system interface is described. The scenario mayuse the structure of the system described in FIG. 6. That is, the APserver exists within a cellular system, and the AP server may beconnected to the MME or the new entity through a new cellular systeminterface for acquiring AP information. The MME or the new entity, whichis an AP information management entity, may acquire AP information fromthe AP server through a new cellular system interface with the APserver.

FIG. 10 shows an example of a method in which a cellular entity, whichis an AP information management entity, acquires AP information from anAP server according to an embodiment of the present invention. Thecellular entity may be the MME or the new entity.

In step S300, in order for the cellular entity to acquire information ofAP existing within coverage of all or a part of eNBs which the cellularentity manages, the cellular entity transmits a secondary RATconfiguration acquisition service setup request to the AP server.Accordingly, the cellular entity may request service registration to theAP server. For example, the cellular entity may transmit a secondary RATconfiguration acquisition service setup request to the AP server at atime point at which the eNB first turns on power or at a time point thatdetermines that it is necessary to apply convergence of the cellularsystem and the Wi-Fi system to devices within coverage of the eNB.Because AP information is not UE specific information, the secondary RATconfiguration acquisition service setup request may be non-UE associatedsignaling.

In order for the cellular entity to transmit the secondary RATconfiguration acquisition service setup request to the AP server, a newcellular system interface may be defined between the cellular entity andthe AP server. Further, a Command-Code value for identifying thesecondary RAT configuration acquisition service setup requesttransmitted through the new cellular system interface may be defined.The Command-Code value may be allocated by IANA in IETF RFC 5516.

Further, the secondary RAT configuration acquisition service setuprequest may include identifier information of each eNB according to anAP information request range. The identifier information of each eNB mayinclude each eNB ID and cell ID and PLMN ID of each eNB. A combinationof PLMN ID, eNB ID, and cell ID may be a format of ECI or ECGI. Further,the secondary RAT configuration acquisition service setup request mayadditionally include a request range flag of each eNB and a location andcoverage of each eNB. When the request range flag is ‘all’, thisrepresents that each eNB requests information of APs within a managingentire cell. When the request range flag is ‘specific cell(s)’, thisrepresents that each eNB requests information of an AP within a specificcell among managing cells. Further, like PLMN ID, identifier informationthat is common to each eNB may be included only one time within thesecondary RAT configuration acquisition service setup request.

In step S310, upon receiving the secondary RAT configuration acquisitionservice setup request from the cellular entity, the AP server transmitsthe secondary RAT configuration acquisition service setup answer to thecellular entity. The secondary RAT configuration acquisition servicesetup answer may include AP information according to a request of thecellular entity. The AP server may extract information of an AP withincoverage of a minimum unit (e.g., a cell) of a request according to anAP information request range and include the information in thesecondary RAT configuration acquisition service setup answer. Further,the secondary RAT configuration acquisition service setup answer mayinclude a request code to the request of the cellular entity, PLMN ID,eNB ID, cell ID, and a location and coverage of the eNB. The secondaryRAT configuration acquisition service setup answer may be transmittedthrough a newly defined cellular system interface between the AP serverand the cellular entity. A Command-Code value for identifying thesecondary RAT configuration acquisition service setup answer may bedefined. The Command-Code value may be allocated by IANA in IETF RFC5516.

AP information on a minimum unit of a request included in the secondaryRAT configuration acquisition service setup answer may include a MACaddress (BSSID) of the AP, SSID of the AP, information (CSG andpassword/OSG) on whether the AP is AP in which only a limited user canuse, HESSID of the AP, information (operating class, channel number) ona frequency channel in which the AP uses, and a location of the AP.

The result code included in the secondary RAT configuration acquisitionservice setup answer may be set to one of ‘success’, ‘failure 1’, and‘failure 2’. A result code set to ‘success’ represents that a request ofthe cellular entity was succeeded. A result code set to ‘failure 1’represents that a request of the cellular entity was failed. A resultcode set to ‘failure 2’ represents that the request of the cellularentity may not be satisfied at a time point that receives a request ofthe cellular entity, but may be satisfied later. When the result code isset to ‘failure 2’, the AP server may further include a time point thatresponds a request of the cellular entity in the secondary RATconfiguration acquisition service setup answer. Alternatively, the APserver may notify the cellular entity that the AP server may respond ata time point that may respond to a request of the cellular entity or maytransmit corresponding AP information at a time point that may respondto the request of the cellular entity.

Upon receiving the secondary RAT configuration acquisition service setupanswer from the AP server, the cellular entity determines a result codewithin the secondary RAT configuration acquisition service setup answer.When the result code is ‘success’, the cellular entity stores receivedAP information on a minimum unit of a request. When the result code is‘failure 1’, the cellular entity no longer requests AP information. Whenthe result code is ‘failure 2’, the cellular entity awaits until a timepoint, at which the AP server can respond to a request of the cellularentity, included in the secondary RAT configuration acquisition servicesetup answer. The cellular entity may request again later AP informationat a time point at which the AP server can respond to the request of thecellular entity.

Hereinafter, a method in which an entity of a secondary RAT systemupdates information of a primary RAT system through a secondary RATconnection with a general device and updates information thereof to amanagement device through a wired network of the secondary RAT systembased on the acquired information of the primary RAT system according toan embodiment of the present invention is described. Information of theprimary RAT system in which the entity of the secondary RAT systemacquires may include an ID of an entity (e.g., a serving base stationand an MME) of the primary RAT system, and location information usingand location technology. Hereinafter, for convenience of thedescription, it is assumed that the primary RAT system is 3GPP LTE (or3GPP LTE-A), which is a cellular system and the secondary RAT system isWi-Fi, which is a WLAN system, and it is assumed that the entity of thesecondary RAT system is an AP. The management device may be theabove-described AP server. Further, the management device may be adevice that provides ANDSF. Further, the general device may be amulti-RAT device that supports a plurality of RATs. In the followingdescription, a general device and a multi RAT device may be mixed andused.

FIG. 11 is an example of a method of acquiring information on a cellularsystem using a multi-RAT device in an active state.

In step S400, an AP transmits an advanced primary RAT system informationrequest (ARSI-REQ) frame to the multi-RAT device so that the informationon the cellular system is requested to the multi-RAT device. TheARSI-REQ frame may have a format of a management MAC frame of anexisting IEEE 802.11.

In step S410, the multi-RAT device transmits an advanced primary RATsystem information response (ARSI-RSP) frame as a response to theARSI-REQ frame to the AP through Wi-Fi wireless connection so that theinformation on the cellular system is transferred to the AP. TheARSI-RSP frame may have a format of a management MAC frame of anexisting IEEE 802.11. The ARSI-RSP frame may include a result(accept/reject) for the request of the AP. It is assumed that themulti-RAT device accepts a request of the AP in FIG. 11.

In step S420, upon receiving the ARSI-RSP frame from the multi-RATdevice, the AP transmits an advanced primary RAT system informationreport (ARSI-REP) frame to a management server so that the acquiredinformation on the cellular system is transferred. When additionalinformation is required, steps S100 to step S120 may be repeatedlyperformed.

FIG. 12 is an example of a method of acquiring information on a cellularsystem using a multi-RAT device in an idle state.

In step S500, an AP transmits an ARSI-REQ frame to the multi-RAT deviceso that the information on the cellular system is requested to themulti-RAT device. The ARSI-REQ frame may have a format of a managementMAC frame of an existing IEEE 802.11. The AP may select at least onemulti-RAT device from all multi-RAT devices which has Wi-Fi wirelessconnection with the AP. This is because a form of a hierarchical networkmust be considered.

In step S510, the multi-RAT device may receive a primary synchronizationsignal (PSS)/secondary synchronization signal (SSS) from the basestation or a system information block (SIB) through a broadcast channel(BCH) in order to acquire information on the cellular system. Themulti-RAT device may perform a TAU procedure with the base station.

In step S520, the multi-RAT device transmits an ARSI-RSP frame as aresponse to the ARSI-REQ frame to the AP through Wi-Fi wirelessconnection so that the information on the cellular system is transferredto the AP. The ARSI-RSP frame may have a format of a management MACframe of an existing IEEE 802.11. The ARSI-RSP frame may include aresult (accept/reject) for the request of the AP. It is assumed that themulti-RAT device accepts a request of the AP in FIG. 12. Further, it isassumed to approve that the cellular system and the multi-RAT devicetransfer information on the cellular system to other system.

In step S530, upon receiving the ARSI-RSP frame from the multi-RATdevice, the AP transmits an ARSI-REP frame to a management server sothat the acquired information on the cellular system is transferred.When additional information is required, steps S100 to step S120 may berepeatedly performed.

When describing a method in which an AP updates information of a primaryRAT system using a general device according to an embodiment of thepresent invention, it is assumed that a multi RAT device, havingreceived an ARSI-REQ frame transmitted from the AP, has alreadytransmitted information of the primary RAT system to the AP.

In various situations, APs may update information of the primary RATsystem. First, when information of the primary RAT system is changed,the AP may update information of the primary RAT system. For example,when information of the primary RAT system is changed, which is a veryrare case, the AP may update information of the primary RAT system. Thatis, even if state of a Wi-Fi link between the AP and the general deviceis a predetermined level or more, but when at least one of informationof the primary RAT system which the general device transmits to the APis changed, the AP may update information of the primary RAT system.Changeable information of the primary RAT system may include a networkidentifier, a BS controller identifier, and a cell/BS identifier. Asanother example, when a cellular cell or a base station is changed as ageneral device moves, the AP may update information of the primary RATsystem. That is, even if state of a Wi-Fi link between the AP and thegeneral device is a predetermined level or more, but when the generaldevice moves to another cellular cell or a base station, the AP mayupdate information of the primary RAT system.

Alternatively, when other information instead of information of theprimary RAT system is changed, the AP may update information of theprimary RAT system. For example, when location information (e.g., acoordinate) of the general device is changed, the AP may updateinformation of the primary RAT system. That is, even if state of a Wi-Filink between the AP and the general device is a predetermined level ormore, but if location information which the general device transmits tothe AP deviates from a change range, the AP may update information ofthe primary RAT system. In this case, the cellular cell or the basestation is not changed.

Alternatively, information of the primary RAT system is not updated, butwhen a device to transmit information of the primary RAT system to theAP should be changed, the AP may update information. For example, whenthe AP should acquire information of the primary RAT system usinganother general device as an existing general device moves, the AP mayupdate information. That is, when state of a Wi-Fi link between the APand the general device drops to less than a predetermined level (asituation in which the general device may deviate from coverage of theAP), the AP may update information.

When the AP requests information of the primary RAT system to thegeneral device through the Wi-Fi link, the AP may notify the generaldevice of an update configuration of the primary RAT system information.That is, update configuration of the primary RAT system information maybe included in an ARSI-REQ frame. Update configuration of the primaryRAT system information may include an update method of the primary RATsystem information and/or a location change range of the general device.The location change range of the general device may be included onlywhen the AP requests location information of the general device. Forexample, a location change range of the general device may be 50 m.

An update method may be divided into periodic transmission and eventtriggered transmission. In periodic transmission, the AP may transmit aparameter such as an update transmission cycle to a general device.Accordingly, the general device may periodically transmit information ofthe primary RAT system to the AP.

In event triggered transmission, only when an update condition issatisfied, the general device may transmit information of the primaryRAT system to the AP. That is, as described above, when an updatecondition is satisfied such as when information of the primary RATsystem is changed, when other information is changed, or when the deviceis changed, the general device may transmit information of the primaryRAT system to the AP. In this case, an update method may be changedaccording to an action code. For example, an update method according toan action code may be as follows.

-   Action 1: Only when a state of the general device is an “active    mode” in the primary RAT system, a corresponding information request    is accepted.-   Action 2: a corresponding information request is accepted regardless    of a state of the general device in the primary RAT system.-   Action 3: Identifier information of a network (e.g., PLMN) of the    primary RAT system is requested.-   Action 4: Identifier information of a BS controller (e.g., MME) of    the primary RAT system is requested.-   Action 5: Identifier information of a cell or a BS (including all    kinds of BS such as a macro BS, a femto BS, and a pico BS) of the    primary RAT system is requested.-   Action 6: Location information (e.g., a coordinate) of a general    device is requested.

As described above, upon receiving an ARSI-REQ frame, the general devicetransmits an ARSI-RSP frame to the AP (refer to step S410 of FIG. 11 andstep S520 of FIG. 12). A frame body field of the ARSI-RSP frame mayinclude a result parameter representing a result (accept/reject) of arequest of the AP. Further, a frame body field of the ARSI-RSP frame mayinclude a reason parameter representing a cause of a result of a requestof the AP. When the result parameter is accept, the reason parameter maybe omitted or may be set to a meaningless value. Therefore, when aresult parameter is ‘reject’, the reason parameter may be generallyincluded. For example, the reason parameter may be one of a case inwhich the general device cannot perform a request of the AP because aprimary RAT system or a general device does not allow to transmitinformation of the primary RAT system to another system (‘not support’),or a case in which a general device cannot perform a request of the APbecause a state of the general device and the primary RAT system is nota suitable state such as an active mode (‘not suitable’).

Further, a frame body field of an ARSI-RSP frame may include an outputparameter representing primary RAT system information corresponding toan action code according to a request of the AP and information onwhether the output parameter is included. For example, when the actioncode is 3, the output parameter may include identifier information of anetwork (e.g., PLMN) of the primary RAT system. For example, when theaction code is 4, the output parameter may include identifierinformation of a BS controller (e.g., a MME) of the primary RAT system.For example, when the action code is 5, the output parameter may includeidentifier information of a cell or a BS (including all kinds of BS suchas a macro BS, a femto BS, and a pico BS) of the primary RAT system. Forexample, when the action code is 6, the output parameter may includelocation information (e.g., a coordinate) of a general device.

Meanwhile, upon receiving the ARSI-REQ frame including an update methodaccording to an embodiment of the present invention, the general devicetransmits an unsolicited ARSI-RSP frame to the AP according to an updatemethod. A frame body field of the unsolicited ARSI-RSP frame may includea result parameter representing a result (accept/reject) of a request ofthe AP. Further, a frame body field of the unsolicited ARSI-RSP framemay include a reason parameter representing a cause of a result of arequest of the AP. When the result parameter is accept, the reasonparameter may be omitted or may be set to a meaningless value.Therefore, when a result parameter is ‘reject’, a reason parameter maybe generally included. For example, the reason parameter may be one acase in which a general device cannot perform a request of a AP becausethe primary RAT system or the general device does not allow to transmitinformation of the primary RAT system to another system (‘not support’),or a case in which a general device cannot perform a request of a APbecause a state between a general device and a primary RAT system is nota suitable state such as an active mode (‘not suitable’), or a case inwhich a general device can no longer update information of a primary RATsystem because state of a Wi-Fi link with the AP is dropped to less thana predetermined level (‘not good’).

Further, a frame body field of an unsolicited ARSI-RSP frame may includean output parameter representing primary RAT system informationcorresponding to an action code according to a request of the AP. Theoutput parameter may include primary RAT system informationcorresponding to all action codes according to a request of the AP oronly changed primary RAT system information. For example, when theaction code is 3, the output parameter may include identifierinformation of a network (e.g., PLMN) of the primary RAT system. Forexample, when the action code is 4, the output parameter may includeidentifier information of a BS controller (e.g., the MME) of the primaryRAT system. For example, when the action code is 5, the output parametermay include identifier information of a cell or a BS (including allkinds of BS such as a macro BS, a femto BS, and a pico BS) of theprimary RAT system. For example, when the action code is 6, the outputparameter may include location information (e.g., a coordinate) of thegeneral device. Only when a location of the general device deviates froma location change range, location information of the general device maybe included.

Upon receiving the unsolicited ARSI-RSP frame, the AP may performoperation according to a result parameter included in the unsolicitedARSI-RSP frame. When a result parameter is ‘reject’, the AP may transmitagain an ARSI-REQ frame. Such a case may correspond to a case in which atarget device in which the AP requests information of the primary RATsystem is changed. That is, a reason parameter included in theunsolicited ARSI-RSP frame may be ‘not good’. In this case, the AP maytransmit an ARSI-REQ frame to another general device instead of ageneral device which transmitted the unsolicited ARSI-RSP frame.Alternatively, even if the AP does not receive a unsolicited ARSI-RSPframe, when state of a Wi-Fi link with the general device which the APmeasures is dropped to less than a predetermined level, the AP maytransmit an ARSI-REQ frame to a new general device.

When a result parameter included in the unsolicited ARIS-RSP frame is‘accept’, the AP compares a previously acquired output parameter and anoutput parameter newly received through the unsolicited ARSI-RSP frame,and only when two output parameters are different, the AP may transmitchanged information of the primary RAT system to an AP informationmanagement device such as the AP server. This corresponds to step S420of FIG. 11 and step S530 of FIG. 12. Such a case may correspond to acase in which information of the primary RAT system or other informationis changed. In this case, when the AP may estimate a location thereofbased on location information of the general device within theunsolicited ARSI-RSP frame, the AP may transmit also estimated locationinformation thereof to the AP information management device. Further,the AP may transmit information thereof such as SSID/BSSID, information(CSG and password/OSG) on whether the AP is an AP in which only alimited user can use, HESSID, and information (operating class, channelnumber) of a using frequency channel to the AP information managementdevice. As a new entity is added between the AP and the AP informationmanagement device, the new corresponding entity may collect informationof the primary RAT system in which the AP transmits, and may transmitthe collected information to the AP information management device bychanging a transmission format. An added new entity may be a dual-stackgateway or an AP controller. The AP and the corresponding entity maypreviously know information (e.g., address) about the AP informationmanagement device or may acquire information (e.g., address) about theAP information management device through an authentication server by anauthentication process. Upon receiving the ARSI-REP frame, the AP serverstores and manages parameter information within the ARSI-REP frame.

Hereinafter, a method in which an AP information management entitywithin a cellular network acquires newest AP information from the APserver is described. This may be described additionally to a method inwhich an AP information management entity acquires AP information fromthe AP server according to an embodiment of the present invention, asdescribed in FIGS. 6 to 10.

1) When the eNB, which is an AP information management entity, acquiresAP information from the AP server through the MME according to anembodiment of FIGS. 6 and 7, a method of updating information of asecondary RAT system for the eNB, which is the AP information managemententity, is described. When transmitting a secondary RAT informationrequest or a secondary RAT configuration acquisition service setuprequest, the eNB or the MME may notify the AP server of an updateconfiguration of AP information, i.e., an update method such as periodictransmission or event triggered transmission. The AP server transmitsupdated AP information to the eNB, which is an AP information managemententity, according to an update method of AP information. When an updatemethod is periodic transmission, even if AP information is not changed,the AP server periodically transmits entire AP information to the eNB,which is an AP information management entity, via the MME. When anupdate method is event triggered transmission, if changed AP informationexists, the AP server transmits the changed AP information to the eNB,which is an AP information management entity, via the MME.

The AP server transmits an update message including AP informationaccording to an update method to the MME. The update message may be asecondary RAT configuration acquisition service setup answer. The APserver may transmit an update message to a previously requested MME orto a new MME to which an eNB to which a corresponding AP moves belongs.Because the AP and the AP server can acquire information about a new MMEthrough a general device, the AP server may transmit an update messageto the changed MME. The update message may be transmitted through anewly defined cellular system interface between the AP server and theMME. A Command-Code value for identifying the update message may bedefined. The Command-Code value may be allocated by IANA in IETF RFC5516.

The update message may include an update flag. The update flag may existper each AP. The update flag may include a parameter such as ‘add’,‘modify’, ‘no change’, and ‘delete’. ‘Add’ represents that newinformation of the AP is transmitted. ‘Modify’ represents thatpreviously transmitted information of the AP is changed. ‘No change’represents that information of the AP is the same as previouslytransmitted information of the AP. ‘Delete’ represents that previouslytransmitted information of the AP is no longer valid and should be thusdeleted. Further, the update message may include AP information such asPLMN ID, eNB ID, cell ID, a location and coverage, a MAC address (BSSID)of the AP, SSID of the AP, information CSG and password/OSG) on whetherthe AP is an AP in which only a limited user can use (HESSID of the AP,and information (operating class, channel number) about a frequencychannel in which the AP uses and an AP location, in addition to theupdate flag.

Upon receiving the update message from the AP server, the MME transmitsAP information corresponding to each eNB included in the update messageto a corresponding eNB. The update message may be secondary RATinformation request acknowledge. In this case, when a MME to which aneNB to which a corresponding AP moves belongs is different from aprevious MME, the previous MME may transmit an update message to a neweNB through a new MME. The update message may be transmitted using a S1application protocol.

The MME performs the following operation according to an update flagwithin the update message received from the AP server.

-   ‘Add’: Information of an AP in which the update flag is ‘add’ is    transmitted to an eNB having coverage overlapped with a    corresponding AP. In this case, the MME may determine a PLMN ID and    eNB ID of a corresponding AP received from the AP server and    determine an eNB to transmit. The update message transmitted to the    eNB includes an action code (‘add’) and AP information on a minimum    unit of a request of each corresponding eNB.-   ‘Modify’: when changed AP information is transmitted to the same eNB    as a previous eNB, an update message transmitted to the eNB includes    an action code (‘modify’) and AP information on a minimum unit of a    request. When the changed AP information is transmitted to an eNB    different from a previous eNB, i.e., when an AP moves to another    eNB, an update message transmitted to the previous eNB to which a    corresponding AP belonged includes an action code (‘delete’) and AP    information on a minimum unit of a request, and an update message    transmitted to a new eNB to which a corresponding AP belongs    includes an action code (‘add’) and AP information on a minimum unit    of a request.

For example, for AP ID 1, it is assumed that previously receivedinformation is PLMN ID 1 and eNB ID 1 and recently received informationis PLMN ID 1 and eNB ID 2. In this case, an update message including anaction code (‘delete’) and AP information (e.g., only an AP identifier)may be transmitted to an eNB in which eNB ID is 1, and an update messageincluding an action code (‘add’)and AP information (e.g., AP BSSID,SSID) may be transmitted to an eNB in which eNB ID is 2. Further, whenthe AP includes new different eNB ID/cell ID together with an existingeNB ID/cell ID, i.e., when the AP is overlapped in coverage of severalbase stations, an update message transmitted to a new eNB to which acorresponding AP belongs includes an action code (‘add’)and APinformation on a minimum unit of a request.

-   ‘No change’: The update message transmitted to the eNB does not    include corresponding AP information.-   ‘Delete’: The update message transmitted to the eNB includes an    action code (‘delete’) and AP information on a minimum unit of a    request.

Upon receiving the update message from the MME, the eNB performsoperation according to an action code within the update message. The eNBstores new information of the AP in which an action code is ‘add’. TheeNB may update information of an AP in which an action code is ‘modify’.The eNB may delete information of an AP in which an action code is‘delete’.

When the AP server is located at the outside of a cellular system, APinformation may be updated with the same method as the above-describedmethod except that an update message transmitted from the AP server tothe MME has a format of an IP packet. Alternatively, even when the APserver is located at the outside of a cellular system and the APinformation management entity is an MME, AP information may be updatedwith the same method as the above-described method. That is, when theMME acquires AP information via a cellular node such as an S-GW and P-GWthrough an existing signaling path, AP information may be updated withthe same method as the above-described method except that the updatemessage transmitted from the AP server to the S-GW and P-GW has a formatof an IP packet. However, the S-GW and the P-GW may perform operation inwhich the MME performs according to the update flag, and the MME mayperform operation in which the eNB performs.

2) When the eNB, which is an AP information management entity, directlyacquires AP information from the AP server according to an embodiment ofFIGS. 8 and 9, a method of updating information of a secondary RATsystem for the eNB, which is the AP information management entity, is bedescribed. When the eNB transmits a secondary RAT configurationacquisition service setup request, the eNB may notify the AP server ofan update configuration of AP information, i.e., an update method suchas periodic transmission or event triggered transmission. The AP servertransmits updated AP information to the eNB, which is an AP informationmanagement entity, according to an update method of AP information. Whenupdate method is periodic transmission, even if AP information is notchanged, the AP server periodically transmits entire AP information tothe eNB, which is an AP information management entity. When an updatemethod is event triggered transmission, if changed AP informationexists, the AP server transmits the changed AP information to the eNB,which is an AP information management entity.

The AP server transmits an update message to the eNB. The update messagemay be a secondary RAT configuration acquisition service setup answer.The update message may be transmitted through a newly defined cellularsystem interface between the AP server and the eNB. A Command-Code valuefor identifying the update message may be defined. The Command-Codevalue may be allocated by IANA in IETF RFC 5516.

The update message may include an update flag. The update flag may existper each AP. The update flag may include a parameter such as ‘add’,‘modify’, ‘no change’, and ‘delete’. ‘Add’ represents that newinformation of the AP is transmitted. When eNB ID of the same AP ischanged, i.e., when a corresponding AP moves to another eNB, an updateflag of the corresponding AP within an update message transmitted to anew eNB to which a corresponding AP belongs is set to ‘add’. ‘Modify’represents that previously transmitted information of the AP is changed.When the changed AP information is transmitted to the same eNB as theprevious eNB, an update flag of a corresponding AP within the updatemessage transmitted to the eNB is set to ‘modify’. ‘No change’represents that information of the AP is the same as previouslytransmitted information of the AP. ‘Delete’ represents that previouslytransmitted information of the AP is no longer valid and should be thusdeleted. When an eNB ID is changed for the same AP, i.e., when acorresponding AP moves to another eNB, an update flag of thecorresponding AP within an update message transmitted to a previous eNBto which a corresponding AP belonged is set to ‘delete’. Further, theupdate message may include AP information such as PLMN ID, eNB ID, cellID, a location and coverage, a MAC address (BSSID) of the AP, SSID ofthe AP, information (CSG and password/OSG) on whether the AP is an AP inwhich only a limited user can use, HESSID of the AP, and information(operating class, channel number) about a frequency channel in which theAP uses and an AP location, in addition to the update flag. Because theupdate message is transmitted to a specific eNB, PLMN ID and eNB ID maybe a ground that determines whether a corresponding update message isvalid to the eNB. Alternatively, PLMN ID and eNB ID may be omitted. TheeNB may update AP information according to the update flag.

When the AP server is located at the outside of a cellular system, andwhen the eNB, which is an AP information management entity, acquires APinformation through a data path generated through the MME or acquires APinformation using data path information of an already known generaldevice, in order to acquire AP information, AP information may beupdated with the same method as the above-described method except thatthe update message transmitted from the AP server to the eNB has aformat of an IP packet.

3) When an MME or a new entity, which is an AP information managemententity, acquires AP information from the AP server according to anembodiment of FIG. 10, a method of updating information of a secondaryRAT system for the MME or the new entity, which is an AP informationmanagement entity, is described. When transmitting a secondary RATconfiguration acquisition service setup request, the MME or the newentity may notify the AP server of an update configuration of APinformation, i.e., an update method such as periodic transmission orevent triggered transmission. The AP server transmits updated APinformation to the MME or the new entity, which is an AP informationmanagement entity, according to an update method of AP information. Whenan update method is periodic transmission, even if AP information is notchanged, the AP server periodically transmits entire AP information tothe MME or the new entity, which is an AP information management entity.When an update method is event triggered transmission, if changed APinformation exists, the AP server transmits the changed AP informationto the MME or the new entity, which is an AP information managemententity.

The AP server transmits an update message to the MME or the new entity.The update message may be a secondary RAT configuration acquisitionservice setup answer. The update message may be transmitted through anewly defined cellular system interface between the AP server and theMME or the new entity. A Command-Code value for identifying the updatemessage may be defined. The Command-Code value may be allocated by IANAin IETF RFC 5516.

The update message may include an update flag. The update flag may existon each AP basis. The update flag may include a parameter such as ‘add’,‘modify’, ‘no change’, and ‘delete’. ‘Add’ represents that newinformation of the AP is transmitted. ‘Modify’ represents thatpreviously transmitted information of the AP is changed. ‘No change’represents that information of the AP is the same as previouslytransmitted information of the AP. ‘Delete’ represents that previouslytransmitted information of the AP is no longer effective and should bethus deleted. Further, the update message may include AP informationsuch as PLMN ID, eNB ID, cell ID, a location and coverage, a MAC address(BSSID) of the AP, SSID of the AP, information (CSG and password/OSG) onwhether the AP is an AP in which only a limited user can use, HESSID ofthe AP, and information (operating class, channel number) about afrequency channel in which the AP uses and an AP location, in additionto the update flag. The MME or the new entity may update AP informationaccording to the update flag.

When the AP server is located at the outside of a cellular system, andwhen the MME, which is an AP information management entity, generates adata path or newly defines a data path other than an existing signalingpath and acquires AP information through the corresponding data path, APinformation may be updated with the same method as the above-describedmethod except that an update message transmitted from the AP server tothe MME has a format of an IP packet.

FIG. 13 is a block diagram showing wireless communication system toimplement an embodiment of the present invention.

An AP server 800 includes a processor 810, a memory 820, and a radiofrequency (RF) unit 830. The processor 810 may be configured toimplement proposed functions, procedures, and/or methods in thisdescription. Layers of the radio interface protocol may be implementedin the processor 810. The memory 820 is operatively coupled with theprocessor 810 and stores a variety of information to operate theprocessor 810. The RF unit 830 is operatively coupled with the processor810, and transmits and/or receives a radio signal.

An eNB, MME, or new entity of a cellular system 900 may include aprocessor 910, a memory 920 and a RF unit 930. The processor 910 may beconfigured to implement proposed functions, procedures and/or methodsdescribed in this description. Layers of the radio interface protocolmay be implemented in the processor 910. The memory 920 is operativelycoupled with the processor 910 and stores a variety of information tooperate the processor 910. The RF unit 930 is operatively coupled withthe processor 910, and transmits and/or receives a radio signal.

The processors 810, 910 may include application-specific integratedcircuit (ASIC), other chipset, logic circuit and/or data processingdevice. The memories 820, 920 may include read-only memory (ROM), randomaccess memory (RAM), flash memory, memory card, storage medium and/orother storage device. The RF units 830, 930 may include basebandcircuitry to process radio frequency signals. When the embodiments areimplemented in software, the techniques described herein can beimplemented with modules (e.g., procedures, functions, and so on) thatperform the functions described herein. The modules can be stored inmemories 820, 920 and executed by processors 810, 910. The memories 820,920 can be implemented within the processors 810, 910 or external to theprocessors 810, 910 in which case those can be communicatively coupledto the processors 810, 910 via various means as is known in the art.

In view of the exemplary systems described herein, methodologies thatmay be implemented in accordance with the disclosed subject matter havebeen described with reference to several flow diagrams. While forpurposed of simplicity, the methodologies are shown and described as aseries of steps or blocks, it is to be understood and appreciated thatthe claimed subject matter is not limited by the order of the steps orblocks, as some steps may occur in different orders or concurrently withother steps from what is depicted and described herein. Moreover, oneskilled in the art would understand that the steps illustrated in theflow diagram are not exclusive and other steps may be included or one ormore of the steps in the example flow diagram may be deleted withoutaffecting the scope and spirit of the present disclosure.

What is claimed is:
 1. A method for transmitting, by an eNodeB (eNB) ofa cellular system, a message in a wireless communication system, themethod comprising: transmitting a request for information on an accesspoint (AP) of a wireless local area network (WLAN) system to an entityof the WLAN system over a newly defined interface between the eNB andthe WLAN system, wherein the request message includes an identifier (ID)of the eNB; and receiving a response of the request including a resultof the request, which is failure, from the entity of the WLAN systemover the newly defined interface between the eNB and the WLAN system. 2.The method of claim 1, wherein the request message further includes atleast one of a request range flag, a cell ID, a public land mobilenetwork (PLMN) ID, location of the eNB, or coverage of the eNB.
 3. Themethod of claim 1, wherein the ID of the eNB is one of an E-UTRAN cellidentifier (ECI) or an E-UTRAN cell global identifier (ECGI).
 4. Themethod of claim 1, wherein the information on the AP includes at leastone of a media access control (MAC) address of the AP, a service setidentifier (SSID) of the AP, a homogeneous extended service set ID(HESSID) of the AP, whether the AP is used by a limited user,information on a frequency channel used by the AP, or a position of theAP.
 5. The method of claim 1, wherein the AP is located within coverageof a cell managed by the eNB.
 6. An eNodeB (eNB) of a cellular system ina wireless communication system, the eNB comprising: a memory; and aprocessor, coupled to the memory, that: transmitting a request forinformation on an access point (AP) of a wireless local area network(WLAN) system to an entity of the WLAN system over a newly definedinterface between the eNB and the WLAN system, wherein the requestmessage includes an identifier (ID) of the eNB; and receiving a responseof the request including a result of the request, which is failure, fromthe entity of the WLAN system over the newly defined interface betweenthe eNB and the WLAN system.
 7. The eNB of claim 6, wherein the requestmessage further includes at least one of a request range flag, a cellID, a public land mobile network (PLMN) ID, location of the eNB, orcoverage of the eNB.
 8. The eNB of claim 6, wherein the ID of the eNB isone of an E-UTRAN cell identifier (ECI) or an E-UTRAN cell globalidentifier (ECGI).
 9. The eNB of claim 6, wherein the information on theAP includes at least one of a media access control (MAC) address of theAP, a service set identifier (SSID) of the AP, a homogeneous extendedservice set ID (HESSID) of the AP, whether the AP is used by a limiteduser, information on a frequency channel used by the AP, or a positionof the AP.
 10. The eNB of claim 6, wherein the AP is located withincoverage of a cell managed by the eNB.